javax.mail.event
Class FolderEvent

This class models Folder existence events. FolderEvents are
delivered to FolderListeners registered on the affected Folder as
well as the containing Store.

Service providers vary widely in their ability to notify clients of
these events. At a minimum, service providers must notify listeners
registered on the same Store or Folder object on which the operation
occurs. Service providers may also notify listeners when changes
are made through operations on other objects in the same virtual
machine, or by other clients in the same or other hosts. Such
notifications are not required and are typically not supported
by mail protocols (including IMAP).